Abstract:A theoretical discussion based on the energy equations suggests that the latent heat of condensation during the rainstorm process is a main factor in the formation of low-level jet streams. A physical mechanism is proposed. Then a three-layer numerical model using the primitive equations is described,the result of which is found to be consistent with the theoretical analysis and observed facts.

Abstract:A simplified one-and-one-half-dimensional,time - independent warm cumulus model is given after simplification and adjustment of the relevant dynamical and physical equations accounting for the main meso- or intermediate-scale characteristics of the cumulus clusters on the Meiyu front. Radiosonde data for Nanjing and Xuzhou in 1982 were fed into the model. The distribution with altitude and variation with time of such parameters as vertical velocity,temperature,specific humidity and water content in cloud as well as precipitation amount and density,radii and falling velocity of raindrops were calculated. Investigation into the evolution and macro and micro structures of rain clouds in the Meiyu are then made on this basis .Thepossibility of estimating the rainfall amount and intensity in the Meiyu front with the cloud model is discussed.

Abstract:By way of a low-order spectral model,the two-layzer quasi-geostrophic model is translated into an eighthorder set of nonlinear ordinary differential equations in which the thermal forcing and dissipative effect are incorporated. Within a certain range of the parameter θ_C^*,which approximately describes the S-N thermal forcing between the subtropical continent and the ocean to the south,an equilibrium of the flow pattern is exhibited. When the θ_C^* value exceeds the critical point,a periodical zonal oscillation of the subtropical high cells can be stimulated showing various oscillational forms.

Abstract:Through using the aerological data of August-September,1982,the energy exchange and its oscillation between the eastern and western monsoon regions in Asia are calculated and analyzed. It is found that various kinds of energy are transported from the plateau monsoon region to the North China monsoon region whereas sensible heat,potential and kinetic energy are transported from South China Sea monsoon region to Indian monsoon region. These transports primarily take place in the upper troposphere. It is worthy to note that latent energy,though small in amount,is transported mainly by the low-level southwesterlies from Indian monsoon region to South China Sea,and it is an important factor for the monsoon rainfall. The predominant oscillation periods of the energy flux in the two southern monsoon regions are longer than the two northern monsoon regions,being about two weeks and four weeks for the former and about two weeks and three weeks for the latter. The oscillation period at upper level is longer than at lower level,with the weekly oscillation mainly occurring at the lower levels. Difference in initial phase may exist between the upper and lower levels even though the periods are identical. This phase lag is probably an important cause of periodic occurrence of strong convective weather.

Abstract:Through the expansion of the monthly mean height fields at 500 hPa level,some statistical features of the main expansion coefficients and parameters of the harmonic wave are calculated. The results are helpful for the determination of seasonal variation of monthly mean height fields.

Abstract:Some aspects of equilibria,bifurcation and catastrophe of the nonlinear inertial motions are discussed. It is suggested that a disturbed air parcel which is inertially stable in the traditional sense may attain a new position rather than return to its original location due to nonlinear effects controlled by the local forcing. The air parcel may also "leap" from one equilibrium position to another. The sudden change of motion states may be caused by the gradual variation of intensity or frequency of the local forcing. This can account for certain behavior of the "index cycle" in the atmosphere.

Abstract:Based on the data of direct clear-sky radiation from 68 observing stations in China,a discussion is made in detail of the computation methods for atmospheric transparency coefficients P₂,P_d and P_w,whereupon a new and more reasonable method for calculating the components P_L,P_d and P_w is Suggested. The main factors affecting atmospheric transparency are analyzed and the spatial distribution of P₂,P_d and P_w is plotted. A discussion of the modes of distribution leads to some interesting results.

Abstract:Torrential rains during the Meiyu over the middle and lower reaches of the Yangtze are one of the most important heavy rainstorms in the flood season. Their radar characteristics such as environmental condition. development and evolution are analyzed.

Abstract:Through a complex analysis of the radar echoes,rainfall observations and radiosonde data of the Meiyu storm over Nanjing on June 24,1983,the distribution and development of the meso-scale rainband within the storm area are discussed in detail. The results show that a mature meso-scale rainband usually generates intense rainfall over a large area.

Abstract:Through an extensive investigation,the following tasks are accomplished: (1) The chief agroclimatic variables of the Yixing hilly area are found to be in good agreement with normal distribution and a method of computing the accumulative negative temperatures by observed maximum and minimum temperatures for predicting frost injury is developed. (2) Each of the agroclimatic variables is analyzed and appraised with reference to the agroclimatic indices for citrus trees,tea bushes and bamboos. (3) Payment function for each crop is established,leading to a quantitative agroclimatic decision plan,which considers agroclimatic historic information,future prediction and economic benefit by Bayes decision method.